András Bors

Distinct clinical characteristics of myeloproliferative neoplasms with calreticulin mutations

Somatic insertions/deletions in the calreticulin gene have recently been discovered to be causative alterations in myeloproliferative neoplasms. A combination of qualitative and quantitative allele-specific polymerase chain reaction, fragment-sizing, high resolution melting and Sanger-sequencing was applied for the detection of three driver mutations (in Janus kinase 2, calreticulin and myeloproliferative leukemia virus oncogene genes) in 289 cases of essential thrombocythemia and 99 cases of primary myelofibrosis. In essential thrombocythemia, 154 (53%) Janus kinase 2 V617F, 96 (33%) calreticulin, 9 (3%) myeloproliferative leukemia virus oncogene gene mutation-positive and 30 triple-negative (11%) cases were identified, while in primary myelofibrosis 56 (57%) Janus kinase 2 V617F, 25 (25%) calreticulin, 7 (7%) myeloproliferative leukemia virus oncogene gene mutation-positive and 11 (11%) triple-negative cases were identified. Patients positive for the calreticulin mutation were younger and had higher platelet counts compared to Janus kinase 2 mutation-positive counterparts. Calreticulin mutation-positive patients with essential thrombocythemia showed a lower risk of developing venous thrombosis, but no difference in overall survival. Calreticulin mutation-positive patients with primary myelofibrosis had a better overall survival compared to that of the Janus kinase 2 mutation-positive (P=0.04) or triple-negative cases (P=0.01). Type 2 calreticulin mutation occurred more frequently in essential thrombocythemia than in primary myelofibrosis (P=0.049). In essential thrombocythemia, the calreticulin mutational load was higher than the Janus kinase 2 mutational load (P<0.001), and increased gradually in advanced stages. Calreticulin mutational load influenced blood counts even at the time point of diagnosis in essential thrombocythemia. We confirm that calreticulin mutation is associated with distinct clinical characteristics and explored relationships between mutation type, load and clinical outcome.

Identification of a DNA Methylation-dependent Activator Sequence in the Pseudoxanthoma Elasticum Gene, ABCC6*

ABCC6 encodes MRP6, a member of the ABC protein family with an unknown physiological role. The human ABCC6 and its two pseudogenes share 99% identical DNA sequence. Loss-of-function mutations of ABCC6 are associated with the development of pseudoxanthoma elasticum (PXE), a recessive hereditary disorder affecting the elastic tissues. Various disease-causing mutations were found in the coding region; however, the mutation detection rate in the ABCC6 coding region of bona fide PXE patients is only ∼80%. This suggests that polymorphisms or mutations in the regulatory regions may contribute to the development of the disease. Here, we report the first characterization of the ABCC6 gene promoter. Phylogenetic in silico analysis of the 5′ regulatory regions revealed the presence of two evolutionarily conserved sequence elements embedded in CpG islands. The study of DNA methylation of ABCC6 and the pseudogenes identified a correlation between the methylation of the CpG island in the proximal promoter and the ABCC6 expression level in cell lines. Both activator and repressor sequences were uncovered in the proximal promoter by reporter gene assays. The most potent activator sequence was one of the conserved elements protected by DNA methylation on the endogenous gene in non-expressing cells. Finally, in vitro methylation of this sequence inhibits the transcriptional activity of the luciferase promoter constructs. Altogether these results identify a DNA methylation-dependent activator sequence in the ABCC6 promoter.

Type and location of isocitrate dehydrogenase mutations influence clinical characteristics and disease outcome of acute myeloid leukemia

Abstract Mutations of isocitrate dehydrogenase 1 and 2 (IDH1/2) are genetic alterations in acute myeloid leukemia (AML). The aim of our study was to investigate the frequency and prognostic effect of IDH1/2 mutations together followed by an individual analysis of each substitution in a Hungarian cohort consisting of 376 patients with AML. IDH1mut and IDH2mut were mutually exclusive, detected in 8.5% and 7.5% of cases, respectively. IDH1/2mut was associated with: older age (p = 0.001), higher average platelet count (p = 0.001), intermediate karyotype (p < 0.0001), NPM1mut (p = 0.022) and lower mRNA expression level of ABCG2 gene (p = 0.006). Overall survival (OS), remission and relapse rates were not different in IDH1mut or IDH2mut vs. IDHneg. IDH1mut and IDH2mut were associated differently with NPM1mut; co-occurrence was observed in 14.3% of IDH1 R132C vs. 70% of R132H carriers (p = 0.02) and in 47.4% of IDH2 R140Q vs. 0% of R172K carriers (p = 0.02). IDH1 R132H negatively influenced OS compared to IDHneg (p = 0.02) or R132C (p = 0.019). Particular amino acid changes affecting the same IDH1 codon influence the clinical characteristics and treatment outcome in AML.

Additional Chromosome Abnormalities, BCR-ABL Tyrosine Kinase Domain Mutations and Clinical Outcome in Hungarian Tyrosine Kinase Inhibitor-Resistant Chronic Myelogenous Leukemia Patients

Background: Additional chromosome abnormalities (ACAs), mutations of the BCR-ABL tyrosine kinase domain (TKD) and BCR-ABL splice variants may cause resistance to first- and second-generation tyrosine kinase inhibitors (TKIs) in chronic myelogenous leukemia (CML) and Philadelphia-positive (Ph+) acute lymphoid leukemia (ALL). Methods: Karyotyping and BCR-ABL TKD mutation screening were performed in 71 imatinib-resistant CML patients and 6 Ph+ ALL patients. A total of 56 out of these 77 patients received second-generation TKI. Results: ACAs were present in 30 of 65 imatinib-resistant patients (46%). In 27 of 74 imatinib-resistant patients (36%), 15 different BCR-ABL TKD mutations were detected. Mutations were found in 25% of chronic-phase patients (12/47), 33% of accelerated-phase patients (5/15), 71% of blast crisis CML patients (5/7) and 100% of ALL patients. In nilotinib-resistant patients, Y253H, T315I and F359I/V mutations were detected; in dasatinib-resistant patients, L248M, E279K and T315I mutations were detected. T315I was found more frequently in patients on dasatinib than on imatinib therapy. The presence of ACAs predicted shorter survival during first- and second-generation TKI therapy, while TKD mutations only influenced survival during second-generation TKI therapy. Conclusion: For patients with TKI resistance, mutation and ACA screening may play a role in identifying patients with poorer prognosis.

Less severe clinical manifestations in patients with hereditary angioedema with missense C1INH gene mutations

RSV cleared (Fig 1), with 103 TEE cells/mL by day 117. Weekly palivizumab supplemented intravenous immunoglobulin throughout the transplant. She maintains 100% donor chimerism at 3 years post-transplant, with full immunoreconstitution. Patient 4, aged 6 months, was ventilated for PCP. Adenovirus was detected by using PCR in stool and blood immediately posttransplant andwas treatedwith cidofovir. Fever and adenoviremia remitted by day 80. CD3 cells were consistently more than 100 cells/mL from day 39 (see Fig E1 in this article’s Online Repository at www.jacionline.org). At 28 months post-transplant, he has full immunoreconstitution. Patient 5, aged 5.5 months, presented with PCP, rhinovirus, human metapneumovirus, and disseminated CMV. Ganciclovir pretransplant was substituted for foscarnet on day 0, when CMV in blood became negative. He developed fever from day 35 with irritability, orofacial dyskinesia, choreiform movements, brisk reflexes, and bilateral clonus. Cranial magnetic resonance imaging and electroencephalogram were normal. A high load of CMV was detected in the cerebrospinal fluid. For 6 weeks, ganciclovir 10 mg/kg was given twice daily to optimize cerebrospinal fluid penetration, with 3 doses of cidofovir. In addition, methylprednisolone 30 mg/kg treated the inflammatory reaction. The CMV titer diminished and was undetectable on day 97. Two hundred thirty-eight CD3 cells/mL on day 60 decreased following immunosuppression with methylprednisolone but rose steadily from day 116 when TEE also began to appear. He appears neurologically normal at 8 months post-transplant with rising numbers of lymphocytes. HLA-haploidentical donor transplants for SCID are diminishing as increasing numbers of cord-stem-cell-transplant procedures are performed. However, children for whom no suitable donor is identified require an HLA-mismatched donor HSCT. We report 5 virally infected patients with SCID who received anti-CD34 stem-cell–selected marrow or CD3/CD19-depleted PBSC HSCT. T Lymphocytes appeared earlier in CD3/CD19depleted recipients than in patients who received CD34 selected stem cells, but both methods led to viral clearance and successful outcome. Our report further demonstrates that TCD transplants can quickly restore immunity to achieve viral clearance in patients with SCID. This is the first report of CD3/CD19depleted grafts in infants with SCID that demonstrates rapid immunoreconstitution and viral clearance in 3 patients. Potential advantages of one method over another will need large prospective trials. Mary Slatter, MD Zohreh Nademi, PhD Sanjay Patel, MD Dawn Barge, PhD Manoj Valappil, MD Ken Brigham, MPhil Sophie Hambleton, PhD Julia Clark, MD Terence Flood, MD Andrew Cant, MD Mario Abinun, DSc Andrew Gennery, MD

The prognostic impact of germline 46/1 haplotype of Janus kinase 2 in cytogenetically normal acute myeloid leukemia.

Background Prognostic risk stratification according to acquired or inherited genetic alterations has received increasing attention in acute myeloid leukemia in recent years. A germline Janus kinase 2 haplotype designated as the 46/1 haplotype has been reported to be associated with an inherited predisposition to myeloproliferative neoplasms, and also to acute myeloid leukemia with normal karyotype. The aim of this study was to assess the prognostic impact of the 46/1 haplotype on disease characteristics and treatment outcome in acute myeloid leukemia. Design and Methods Janus kinase 2 rs12343867 single nucleotide polymorphism tagging the 46/1 haplotype was genotyped by LightCycler technology applying melting curve analysis with the hybridization probe detection format in 176 patients with acute myeloid leukemia under 60 years diagnosed consecutively and treated with curative intent. Results The morphological subtype of acute myeloid leukemia with maturation was less frequent among 46/1 carriers than among non-carriers (5.6% versus 17.2%, P=0.018, cytogenetically normal subgroup: 4.3% versus 20.6%, P=0.031), while the morphological distribution shifted towards the myelomonocytoid form in 46/1 haplotype carriers (28.1% versus 14.9%, P=0.044, cytogenetically normal subgroup: 34.0% versus 11.8%, P=0.035). In cytogenetically normal cases of acute myeloid leukemia, the 46/1 carriers had a considerably lower remission rate (78.7% versus 94.1%, P=0.064) and more deaths in remission or in aplasia caused by infections (46.8% versus 23.5%, P=0.038), resulting in the 46/1 carriers having shorter disease-free survival and overall survival compared to the 46/1 non-carriers. In multivariate analysis, the 46/1 haplotype was an independent adverse prognostic factor for disease-free survival (P=0.024) and overall survival (P=0.024) in patients with a normal karyotype. Janus kinase 2 46/1 haplotype had no impact on prognosis in the subgroup with abnormal karyotype. Conclusions Janus kinase 2 46/1 haplotype influences morphological distribution, increasing the predisposition towards an acute myelomonocytoid form. It may be a novel, independent unfavorable risk factor in acute myeloid leukemia with a normal karyotype.

Co-occurrence of Myeloproliferative Neoplasms and Solid Tumors Is Attributed to a Synergism Between Cytoreductive Therapy and the Common TERT Polymorphism rs2736100

Background: The germline telomerase reverse transcriptase (TERT) rs2736100_C variant was identified as a susceptibility factor for a variety of solid tumors and recently for myeloproliferative neoplasms (MPN). Methods: LightCycler melting curve analysis was applied to detect risk alleles of TERT rs2736100_C and Janus kinase 2 (JAK2) rs12343867_C tagging 46/1 haplotype in 584 BCR-ABL1–negative MPN, 308 acute, and 86 chronic myeloid leukemia (AML and CML) patients and 400 healthy individuals. Results: TERT rs2736100_C showed an increased allele frequency in BCR-ABL1–negative MPN patients compared with controls (62.7%±2.8% vs. 48.8%±3.5%, P < 0.0001) regardless of molecular background or disease type, but not in CML or AML. Combined TERT and JAK2 hetero- or homozygosity conferred even higher risk for classic MPN. Common complications (thrombosis, myelofibrosis, or leukemia) were not associated with the TERT variant; however, adverse survival was noted in TERT variant carrier polycythemia vera patients. MPN patients with the TERT CC genotype had a higher probability (44.4%) to die from solid tumors compared with TERT AC/AA individuals (5.3%; P = 0.004). TERT rs2736100_C carriers had increased risk of solid tumors independently from cytoreductive treatment [3.08 (1.03–9.26), P = 0.045]. Conclusions: TERT rs2736100_C polymorphism predisposes to the development of BCR-ABL1–negative MPN with the co-occurrence of solid tumors, especially with the usage of cytoreductive treatment. Impact: The high frequency of TERT variant in the classic MPN population highlights the importance of the avoidance of long-term cytoreductive treatment in MPN patients. Cancer Epidemiol Biomarkers Prev; 25(1); 98–104. ©2015 AACR.

Medium-sized FLT3 internal tandem duplications confer worse prognosis than short and long duplications in a non-elderly acute myeloid leukemia cohort

Abstract Internal tandem duplications (ITDs) of the fms-like tyrosine kinase 3 (FLT3) gene occur in about 25% of patients with adult acute myeloid leukemia (AML). The aim of our study was to investigate the frequency of FLT3-ITD mutations followed by a detailed analysis of the mutational load and size of ITD insertions in a cohort consisting of 324 patients younger than 60 years old and treated with curative intention. FLT3-ITD alone did not influence overall survival (OS) or disease-free survival (DFS). We observed worse OS and DFS for patients with high mutational load indicative for loss of the FLT3 wild type allele (p = 0.010, p = 0.038, respectively). In multivariate analyses, patients with FLT3-ITD48–60bp showed worse OS and DFS compared to other groups (FLT3-ITDneg, FLT3-ITD < 48b, FLT3-ITD > 60bp; p = 0.014, p = 0.019, respectively). Our novel observation suggested that not only high FLT3-ITD load, but also medium-sized ITD insertions (48–60 bp) represented an adverse prognostic subgroup of patients with AML.

Association of celiac disease and hereditary angioedema due to C1-inhibitor deficiency. Screening patients with hereditary angioedema for celiac disease: is it worth the effort?

Objective Hereditary angioedema due to C1-inhibitor deficiency is a life-threatening condition, which manifests as edematous attacks involving subcutaneous tissues and/or the upper airway/gastrointestinal mucosa. Celiac disease is a gluten-sensitive small intestinal disorder that can lead to severe villous atrophy, malabsorption, and malignancy. Both hereditary angioedema and celiac disease may present with abdominal symptoms. Our aim was to study the occurrence of celiac disease in the hereditary angioedema population, as well as to analyze the clinical course of cases with both diseases. Methods One hundred and twenty-eight patients with hereditary angioedema were screened for celiac disease, using serological methods [antiendomysial antibodies-immunoglobulin A (IgA), antiendomysial antibodies-IgG and tissue transglutaminase-IgA, tissue transglutaminase-IgG]. Clinical data of a child with hereditary angioedema and celiac disease diagnosed earlier were added to the dataset to be analyzed. Thus, the total number of patients was 129, comprising 107 adults and 22 pediatric patients. In patients with celiac disease, molecular genetics analysis (human leukocyte antigen-DQA1, human leukocyte antigen-DQB1) was carried out along with the introduction of a gluten-free diet and regular follow-up. Results Four out of the 22 children were diagnosed with celiac disease in our hereditary angioedema population. The prevalence of celiac disease among our pediatric patients with hereditary angioedema (22 children) was higher than in the general population (18.1 vs. 1.2%). Switching from the wheat starch-containing tranexamic acid product to danazol and introducing a gluten-free diet mitigated abdominal symptoms of hereditary angioedema. Conclusion Similarities between the symptoms of hereditary angioedema and celiac disease may cause difficulties in differential diagnosis, as well as in choosing the appropriate therapy. In our opinion, screening hereditary angioedema patients for celiac disease is warranted if abdominal attacks or neurological symptoms persist despite adequate management. Complement testing is recommended whenever abdominal symptoms persist despite the histological and serological remission of gluten-sensitive enteropathy after the introduction of a gluten-free diet.

Carrier and prenatal diagnostic strategy and newly identified mutations in Hungarian haemophilia A and B families

Deficiencies of blood coagulation factors VIII and IX (haemophilia A and haemophilia B) represent the most common inherited bleeding disorders with a wide range of causative mutations. Carrier and prenatal diagnostics are preferably performed by direct mutation detection; however, in certain situations, indirect family studies may also be useful. We aimed to utilize a combination of direct and indirect techniques for carrier and prenatal diagnostics in both haemophilias in a single national centre. Two hundred and eleven haemophilia A families were investigated by screening for inversions of introns 1 and 22, and by family studies using polymorphic markers. Twenty-eight haemophilia A and 39 haemophilia B families were investigated by Sanger-sequencing of the coding regions. Among severe haemophilia A families, frequencies of intron 22 and 1 inversions were 82 out of 145 (57%) and two out of 145 (1.4%). Sequencing of the entire coding region of the respective factor gene was performed and 12 (haemophilia A) and 5 (haemophilia B) previously unpublished disease-causing mutations were identified. For genetic markers used for haemophilia A indirect family testing, heterozygosity rates varied between 137 out of 327 [42% intragenic BclI restriction fragment length polymorphism (RFLP], 168 out of 254 (66% intragenic F8Civs13CA) and 202 out of 261 (77% extragenic DXS15CA) with a combined rate of 92% (intragenic markers) and 97% (all three markers). For male fetuses, prenatal diagnostics was provided to 43 haemophilia A families (n = 22 with direct mutation detection and n = 21 by indirect family testing) and to three haemophilia B families. The combination of direct and indirect molecular genetics approaches is a successful and cost-effective approach to provide carrier and prenatal diagnostics and risk assessment for inhibitor formation.